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Fixing UB in fastpow #23

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Fixing UB in fastpow #23

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12 changes: 9 additions & 3 deletions util.h
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
#include <string.h>

// Various utility functions mainly for
// imprecise but fast floating point

Expand All @@ -22,9 +24,13 @@ static inline float fastpow2_m1(float x)

static inline float fastpow(float a, float b)
{
union { float f; int i; } u = { a };
u.i = (int) (b * (u.i - 1072632447) + 1072632447.0f);
return u.f;
int i;
float r;

memcpy(&i, &a, sizeof(i));
i = (int)(b * (i - 1072632447) + 1072632447.0f);
memcpy(&r, &i, sizeof(r));
return r;
}

// Very random - but quick - function to smoothly
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